Reinforcing bars are customarily used to provide internal support for concrete forms. Over the years many variations in such reinforcing bars have been introduced as shown in the following patents:
______________________________________ U.S. Pat. Nos. ______________________________________ 4,229,501 3,415,552 4,119,764 3,335,539 3,561,185 3,312,035 1,007,107 2,062,383 3,260,150 3,280,874 3,292,337 3,302,348 3,347,005 3,348,354 3,376,686 3,401,497 3,430,406 3,641,799 3,641,799 3,782,839 3,948,010 3,950,905 3,952,468 3,986,311 3,986,311 4,018,055 4,137,685 4,137,685 4,137,686 4,165,904 4,185,440 4,192,114 4,308,705 4,320,544 4,406,103 4,507,817 4,507,817 4,601,625 4,620,401 815,618 863,959 1,317,824 1,400,278 1,514,806 2,264,480 3,378,985 3,771,884 4,179,583 3,979,186 353,156 (Switzerland) 626,831 (Italy) 636,302 (Canada) ______________________________________
Reinforcing bars have been generally employed to furnish tensile strength to concrete sections subject to bending loads and additional compressive strength when unreinforced concrete would prove too bulky. The deformed reinforcing bars have been used specifically to inhibit longitudinal movement of the bars relative to the surrounding concrete. Although some effort in the prior art has been directed to improve the tensile strength of a given size reinforcing bar, there has not been any substantial effort to reduce the amount of metal required for a reinforcing bar while retaining the same tensile strength, bending load, compressive strength and inhibition against longitudinal movement in concrete.